NOAA Ocean Current Notes

Currents are coherent streams of water moving through the ocean and include both long, permanent features such as the Gulf Stream, as well as smaller, episodic flows in both coastal waters and the open ocean. They are formed primarily by wind blowing across the surface of the ocean and by differences in the temperature, density and pressure of water and are steered by Earth's rotation as well as the location of the continents and topography of the ocean bottom.

Gyres are spiraling circulations thousands of miles in diameter and rimmed by large, permanent ocean currents.

Eddies are smaller, temporary loops of swirling water that can travel long distances before dissipating.

There are only 5 gyres in the world, 1 in the Pacific Ocean, 1 in the Indiana Ocean, and 2 in the Atlantic ocean

It takes a gyre to rotate for about 100- 1,000 years

Currents are caused by gravity, density, and wind

There are two types of density layers in the ocean: Surface Currents-- Surface Circulation and Deep Water Currents--Thermohaline Circulation

Surface currents are driven by gravity

The Coriolis effect makes currents go off course so that's why it goes around so many places

The Gulf stream current

The Gulf Stream is a strong, fast moving, warm ocean current that originates in the Gulf of Mexico and flows into the Atlantic Ocean. It makes up a portion of the North Atlantic Subtropical Gyre.

The majority of the Gulf Stream is known as a western boundary current. This means that it is a current with behavior determined by the presence of a coastline - in this case the eastern United States and Canada - and is found on the western edge of an oceanic basin. Western boundary currents are normally very warm, deep, and narrow currents that carry water from the tropics to the poles.

Currents are affected also by the shape of the ocean floor

Summary:Because ocean currents circulate water worldwide, they have a big impact on the movement of energy and moisture between the oceans and the atmosphere. As a result, they are important to the world’s weather conditions. The Gulf Stream, for example, is a warm current that originates in the Gulf of Mexico and moves north toward Europe. Since it is full of warm water, the sea surface temperatures are warm, which keeps places like Europe warmer than other areas at similar latitudes. The Humboldt Current is another example of a current that affects weather. When this cold current is normally present off the coast of Chile and Peru, it creates extremely productive waters and keeps the coast cool and northern Chile arid. However, when it becomes disrupted, Chile’s climate is altered and it is believed that El Niño plays a role in its disturbance. Like the movement of energy and moisture, debris can also get trapped and moved around the world via currents. This can be man-made which is significant to the formation of trash islands or natural such as icebergs. Currents plan an important role in navigation as well. In addition to being able to avoid trash and icebergs, knowing about currents is essential to the reduction of shipping costs and fuel consumption. Today, shipping companies and even sailing races often use currents to reduce time spent at sea. Finally, ocean currents are important to the distribution of the world’s sea life. Many species rely on currents to move them from one location to another whether it is for breeding or just simple movement over large areas. Today, ocean currents are also gaining significance as a possible form of alternative energy. Because water is dense, it carries an enormous amount of energy that could possibly be captured and converted into a usable form through the use of water turbines. Currently this is an experimental technology being tested by the United States, Japan, China, and some European Union countries. Whether ocean currents are used as alternative energy, to reduce shipping costs, or in their natural to state to move species and weather worldwide, they are very important to geographers, meteorologists, and other scientists because they have a tremendous impact on the globe and earth-atmosphere relations.

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